Study: Obesity Predicts Psoriatic Arthritis

July 19, 2010 -- People who are obese at age 18 may face a higher risk of developing psoriatic arthritis as they grow older, according to a new study.

Using statistical models, researchers led by Razieh Soltani-Arabshahi, MD, of the University of Utah School of Medicine in Salt Lake City, found that a body mass index (BMI) -- a measurement of height and weight -- that indicated obesity at age 18 was predictive of developing psoriatic arthritis, a form of arthritis that affects between 6% and 42% of patients with psoriasis.

All of the patients in the study had psoriasis confirmed by a dermatologist. Psoriatic arthritis diagnoses were made by rheumatologists. BMI was based on the participants’ self-reported height and weight at age 18 and at the time of enrollment.At age 18, 14.1% of the group was considered clinically overweight based on their BMI and 5% was considered obese.At the time of enrollment, 33.5% were overweight and 35.5% were obese.

Based on an evaluation of 943 study participants, Soltani-Arabshahi and colleagues found that:

20% of the overweight or obese participants developed psoriatic arthritis by age 35, compared with the group of participants who had a normal BMI, where 20% did not develop psoriatic arthritis until age 48.

Being younger when psoriasis first occurred, being female, and having larger body surfaces affected with psoriasis also predicted who would develop psoriatic arthritis at a younger age.

The findings are published in Monday’s issue of Archives of Dermatology.

These results, the authors say, "support a growing concept that patients more prone to psoriatic arthritis might benefit from more frequent and meticulous screening measures for early detection and treatment of psoriatic arthritis, i.e., before the development of irreversible joint destruction."

In an accompanying editorial, Alexis Ogdie, MD, and Joel M. Gelfand, MD, from the University of Pennsylvania Hospital, note that psoriatic arthritis symptoms often do not surface until years after the development of psoriasis. This window offers doctors a chance to identify patients at risk for developing psoriatic arthritis.

"Epidemiologic studies evaluating risk factors for psoriatic disease did not start until very recently, and very few environmental risk factors (such as obesity and smoking for psoriasis) have been identified and confirmed in more than one study,” Ogdie and Gelfand write." Ultimately, identification of risk factors for psoriatic arthritis holds the promise of improving our ability to diagnose this condition and prevent it through risk-factor modification."